Ignition timing change-over device

ABSTRACT

An ignition timing change-over device adapted for use with a dual-point distributor to improve engine operation during engine starting and warm-up. The retarding breaker contact of the distributor is connected to the primary side of the ignition coil by way of first and second serially connected relay switches which are normally closed. The first relay switch is adapted to open when its solenoid coil is energized by closing of a starting switch. The second relay switch has a solenoid coil connected to a d.c. voltage source by way of a thermostatically controlled switch which remains closed to energize the solenoid coil of the second relay switch to open during the warm-up operation of the engine. During the engine starting and warm-up operations, either or both of the two relay switches is kept open to interrupt the retarding breaker circuit so that an ignition advance takes place.

ilnited States Patent 91 Mayashi et al.

1 51 Feb. 20, 1973 [54] IGNITION TIMING CHANGE-OVER DEVICE [75]Inventors: Yoshimasa Mayashi, Yukihiro Toh,

both of Yokohama, Japan 521 U.S. (11......123/117 R, 123/179 B, 123/17986,

123/117 A 51 1111.01. ..F02n 17/00, F02p 5/04 58 Field of Search..123/117.1,117, 179 GB [56] References Cited UNITED STATES PATENTS1/1971 Date ..l23/1l7 3/1959 Obermaier ....l23/117 ...l23/117 3,540,422ll/1970 Kelly 1 23/1 17 FOREIGN PATENTS OR APPLICATIONS 177,354 8/1935Germany ..123/1l7 Primary Examiner-Laurence M. Goodridge AssistantExaminer-Ronald B. Cox Attorney-McCarthy, Depaoli, OBrien & Price 5 7ABSTRACT An ignition timing change-over device adapted for use with adual-point distributor to improve engine operation during enginestarting and warm-up. The retarding breaker contact of the distributoris connected to the primary side of the ignition coil by way of firstand second serially connected relay switches which are normally closed.The first relay switch is adapted to open when its solenoid coil isenergized by closing of a starting switch. The second relay switch has asolenoid coil connected to a d.c. voltage source by way of athermostatically controlled switch which remains closed to energize thesolenoid coil of the second relay switch to open during the warm-upoperation of the engine. During the engine starting and warm-upoperations, either or both of the two relay switches is kept open tointerrupt the retarding breaker circuit so that an ignition advancetakes place.

1 Claim, 1 Drawing Figure IGNITION TIMING CHANGE-OVER DEVICE Thisinvention relates to automotive ignition systems and more particularlyto an ignition timing change-over device adapted for use with dual-pointdistributors to improve engine operation during engine starting andwarmup.

In the present day automotive ignition system, it is a usual practice toretard the ignition timing in order to reduce the amount of harmful airpollutants, such as hydrocarbons and nitrogen oxides emitted in engineexhaust gases. However, the retardation of ignition timing tends tocause a reduction in thermal efficiency or power productivity of theengine, which leads to degradation of the driving performance. Thedegradation is represented by the fact that undesirable engine stallfrequently occur under cold atmospheric conditions as in cold weatherand particularly during the engine warm-up operation (for example, untilthe temperature of the coolants reaches about +50C The period of timeover which the engine is under cold operating conditions forms only avery limited period of the entire engine operation. Furthermore, it isfound that under the cold operating conditions there is the leastquantity of nitrogen oxides emitted in the exhaust gases.

It is, therefore, an object of this invention to provide a device foreffecting a change-over of ignition timing for a motor vehicle to haveavailable improved driving performance during the entire engineoperation.

It is another object of this invention to provide a device which isoperative to advance the ignition timing during the engine starting andwarm-up operations and to retard the timing when the engine temperatureis above a predetermined level.

It is a further object of this invention to provide a device adapted foruse with a dual-point type distributor.

In the drawing, there is shown a circuit diagram of an ignition systemaccording to this invention.

The ignition system as depicted comprises a d.c. voltage source orbattery 10, an ignition switch 11, an ignition coil 12, a spark plugwire 13, a spark plug 14 and a distributor 15. Also included in thesystem is a device for controlling or changing over the ignition timing,generally indicated at 16.

The distributor 15 is of any dual-point type having a breaker cam 17 andtwo sets of ignition contacts, one being a retarding breaker contact 18and the other an advancing breaker contact 19. It should be noted thatthe retarding breaker contact 18 is arranged to maintain the ignitiontiming in the neighborhood of or about 10behind top dead center whilethe advancing breaker contact 19 is arranged to maintain the ignitiontiming in the neighborhood of or about ten degrees before top deadcenter. Each of the ignition contacts 18 and 19 consist of a stationarycontact point 20 or 21 connected to ground and a movable contact point22 or 23 attached to an insulated pivotal arm 24 or 25, respectively.The contact arm 25 carrying the advancing breaker movable contact point23 is electrically connected to the primary side 26 of the ignition coil12 and also to a condenser 27 having one 'end connected to ground. Theretarding breaker contact arm 24 is connected to another condenser 28also having one end connected to ground, but the arm 24 is connected tothe primary side 26 of the ignition coil 12 by way of serially connectedswitches 29 and 30, both being normally closed.

These two switches 29 and 30 are usual relay switches that are adaptedto be opened by energization of their respective solenoids 31 and 32.While the solenoids 31 and 32 are de-energized, the contacts of therespective switches 29 and 30 are closed by spring action. Theseswitches 29 and 30 form part of the ignition timing change-over device16 according to this invention.

The solenoid 31 has one terminal connected to the battery 10 through astarting switch 33 and the other terminal grounded. A starting motor 34is also connected to the battery 10 via the starting switch 33. Theother solenoid 32 has one terminal connected to ground and the otherterminal connected to the battery 10 by way of a thermostaticallycontrolled switch 35. The thermostatically controlled switch 35comprises a stationary contact 36 connected to the solenoid coil 32 anda movable contact 37 attached to a spring loaded arm 38 leading to thebattery 10.

A thermostat housing 39 is shown in the lower righthand corner of thedrawing as being mounted on an engine 40 and carrying a bimetal member41 which sense the engine temperature. As shown, the bimetal member 41is operatively connected to the spring loaded arm 38 through amechanical linkage 42 so that when the engine temperature is raised thebimetal member 41 yields, thereby causing the linkage 42 to open theswitch contacts 36 and 37.

Operation of the ignition system according to this invention is suchthat when the starting switch 33 is closed to start the engine 40 thesolenoid coil 31 is energized, causing the switch contact 29 to opensimultaneously with the energization of the starting motor 34. When thisoccurs, a current path from the battery through the ignition switch 11and the primary side 26 of the ignition coil 12 to the retarding breakercontact 18 is interrupted so that an ignition advance takes place.

During the warm-up operation, the engine temperature sensed by thebimetal member 41 is not sufficiently high to cause the bimetal member41 to yield and exert a pressure on the spring loaded arm 38, therebyclosing the switch 35. Thus, the solenoid coil 32 is energized by thebattery 10, opening the relay switch 30. With the switch 30 open, theretarding breaker circuit is not completed and therefore the ignitionadvance is maintained. It will be appreciated that this ignition advanceis effected relative to the normal retarded condition and, therefore,the ignition timing is held in the neighborhood of or about l0before'top dead center.

When the engine temperature is so raised as to cause the bimetal member41 to open the thermostatically controlled switch 35, the solenoid coil32 is de-energized so that the switch 30 is closed. Since the switch 29is kept closed after the engine has been started, a current path fromthe battery 10 to the retarding breaker contact 18 is established. As aresult, the ignition timing is changed over to the retarding side. It isto be noted that by adjusting the actuating point of the bimetal member41 at a desired engine temperature it is possible to change over theignition timing to the normal retarding side upon completion of thewarm-up operation.

As has been described above, this invention provides timing relative tothe normal retarded condition during the engine starting and warm-upoperations thereby to prevent engine stall and to increase engineperformance efficiency. What is claimed is:

1. In an ignition system for an internal combustion engine having a dualpoint distributor, an normally closed relay switches connected in serieswith each other between the retarding breaker contact of the distributorand the primary side of the ignition coil and having respectively asolenoid coil, the solenoid coil of the first named relay switch beingconnected to the dc. voltage source via the starting switch for beingenergized to open the first named relay switch during the

1. In an ignition system for an internal combustion engine having a dualpoint distributor, an normally closed relay switches connected in serieswith each other between the retarding breaker contact of the distributorand the primary side of the ignition coil and having respectively asolenoid coil, the solenoid coil of the first named relay switch beingconnected to the d.c. voltage source via the starting switch for beingenergized to open the first named relay switch during the startingoperation of the engine, a thermostatically controlled switch connectedbetween the solenoid coil of the second named relay switch and saidvoltage source, and a bimetal member adapted for sensing the enginetemperature and for opening said thermostatically controlled switch tode-energize the solenoid coil of the second named relay switch, wherebyan ignition advance of the distributor is effected relative to thenormal retarded condition during the starting and warm-up operations ofthe engine thereby to increase engine performance efficiency.